Known instruments of this general type, to be mounted on the dashboard of a motor vehicle, have stationary scales coacting with respective pointers for respectively indicating speed, consumed fuel and distance traveled. The two last-mentioned data enable a determination of average fuel consumption, e.g. in terms of miles per gallon, to be indicated on a further stationary scale. That average rate of consumption, however, differs from the instant rate which is influenced by a variety of factors including driving speed, road conditions or frequent starts and stops in city traffic.
With the known instruments, accordingly, a driver would not be able to determine whether the vehicle is being handled at any given instant under conditions of low, normal or high fuel consumption.